/*
 * Compilation Copyright (c) 1995-2019 by Wei Dai.  All rights reserved.
 *	This copyright applies only to this software distribution package
 *	as a compilation, and does not imply a copyright on any particular
 *	file in the package.
 * 
 *	Boost Software License - Version 1.0 - August 17th, 2003
 *
 *	Permission is hereby granted, free of charge, to any person or organization
 *	obtaining a copy of the software and accompanying documentation covered by
 *	this license (the "Software") to use, reproduce, display, distribute,
 *	execute, and transmit the Software, and to prepare derivative works of the
 *	Software, and to permit third-parties to whom the Software is furnished to
 *	do so, all subject to the following:
 * 
 *	The copyright notices in the Software and this entire statement, including
 *	the above license grant, this restriction and the following disclaimer,
 *	must be included in all copies of the Software, in whole or in part, and
 *	all derivative works of the Software, unless such copies or derivative
 *	works are solely in the form of machine-executable object code generated by
 *	a source language processor.
 *
 *	THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 *	IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 *	FITNESS FOR A PARTICULAR PURPOSE, TITLE AND NON-INFRINGEMENT. IN NO EVENT
 *	SHALL THE COPYRIGHT HOLDERS OR ANYONE DISTRIBUTING THE SOFTWARE BE LIABLE
 *	FOR ANY DAMAGES OR OTHER LIABILITY, WHETHER IN CONTRACT, TORT OR OTHERWISE,
 *	ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
 *	DEALINGS IN THE SOFTWARE.
 */

// oaep.h - originally written and placed in the public domain by Wei Dai

/// \file oaep.h
/// \brief Classes for optimal asymmetric encryption padding
/// \since Crypto++ 2.1

#ifndef CRYPTOPP_OAEP_H
#define CRYPTOPP_OAEP_H

#include "cryptlib.h"
#include "pubkey.h"
#include "sha.h"

NAMESPACE_BEGIN(CryptoPP)

/// \brief OAEP padding base class
/// \since Crypto++ 2.1
class CRYPTOPP_DLL OAEP_Base : public PK_EncryptionMessageEncodingMethod
{
public:
	bool ParameterSupported(const char *name) const {return strcmp(name, Name::EncodingParameters()) == 0;}
	size_t MaxUnpaddedLength(size_t paddedLength) const;
	void Pad(RandomNumberGenerator &rng, const byte *raw, size_t inputLength, byte *padded, size_t paddedLength, const NameValuePairs &parameters) const;
	DecodingResult Unpad(const byte *padded, size_t paddedLength, byte *raw, const NameValuePairs &parameters) const;

protected:
	virtual unsigned int DigestSize() const =0;
	virtual HashTransformation * NewHash() const =0;
	virtual MaskGeneratingFunction * NewMGF() const =0;
};

/// \brief OAEP padding
/// \tparam H HashTransformation derived class
/// \tparam MGF MaskGeneratingFunction derived class
/// \sa <a href="http://www.weidai.com/scan-mirror/ca.html#cem_OAEP-MGF1">EME-OAEP</a>, for use with classes derived from TF_ES
/// \since Crypto++ 2.1
template <class H, class MGF=P1363_MGF1>
class OAEP : public OAEP_Base, public EncryptionStandard
{
public:
	static std::string CRYPTOPP_API StaticAlgorithmName() {return std::string("OAEP-") + MGF::StaticAlgorithmName() + "(" + H::StaticAlgorithmName() + ")";}
	typedef OAEP<H, MGF> EncryptionMessageEncodingMethod;

protected:
	unsigned int DigestSize() const {return H::DIGESTSIZE;}
	HashTransformation * NewHash() const {return new H;}
	MaskGeneratingFunction * NewMGF() const {return new MGF;}
};

CRYPTOPP_DLL_TEMPLATE_CLASS OAEP<SHA1>;

NAMESPACE_END

#endif
